Adds all of the elements in the specified collection to this set if
they're not already present (optional operation). If the specified
collection is also a set, the {@code addAll} operation effectively
modifies this set so that its value is the <i>union</i> of the two
sets. The behavior of this operation is undefined if the specified
collection is modified while the operation is in progress.
@param c collection containing elements to be added to this set
@return {@code true} if this set changed as a result of the call
@throws UnsupportedOperationException if the {@code addAll} operation
is not supported by this set
@throws ClassCastException if the class of an element of the
specified collection prevents it from being added to this set
@throws NullPointerException if the specified collection contains one
or more null elements and this set does not permit null
elements, or if the specified collection is null
@throws IllegalArgumentException if some property of an element of the
specified collection prevents it from being added to this set
@see #add(Object)
Adds all of the elements in the specified collection to this set if they're not already present (optional operation). If the specified collection is also a set, the {@code addAll} operation effectively modifies this set so that its value is the <i>union</i> of the two sets. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress.
@param c collection containing elements to be added to this set @return {@code true} if this set changed as a result of the call
@throws UnsupportedOperationException if the {@code addAll} operation is not supported by this set @throws ClassCastException if the class of an element of the specified collection prevents it from being added to this set @throws NullPointerException if the specified collection contains one or more null elements and this set does not permit null elements, or if the specified collection is null @throws IllegalArgumentException if some property of an element of the specified collection prevents it from being added to this set @see #add(Object)